Composite multi-stage pulse tube refrigerator working in 1-2K temperature zone

Abstract

The invention discloses a 1-2K composite multi-stage pulse tube refrigerator which comprises a precooling-stage low-frequency pulse tube refrigerator utilizing a helium-4 working medium and a low-temperature-stage high-frequency pulse tube refrigerator utilizing a helium-3 working medium. The high-frequency pulse tube refrigerator is coupled to the low-frequency pulse refrigerator, so that 1-2K refrigeration temperatures can be obtained under the condition that little helium-3 is used. Compared with the traditional double-stage low-frequency pulse tube refrigerator utilizing helium-3 as a working medium, the 1-2K composite multi-stage pulse tube refrigerator has the advantages that consumption of helium-3 gas can be obviously reduced, and the 1-2K composite multi-stage pulse tube refrigerator is low in cost and convenient to implement and keeps characteristics of compact structure, long service life and high reliability of an existing pulse tube refrigerator.

Description

technical field [0001] The invention relates to a composite multistage pulse tube refrigerator, in particular to a high-low frequency composite multistage pulse tube refrigerator which uses helium-4 and helium-3 as working fluids and works in the 1-2K temperature range. Background technique [0002] Low-temperature refrigeration technology has extensive and irreplaceable applications in basic scientific research, low-temperature physics, industrial applications, medical biology, national defense and military, and space exploration. The scientific fields related to low temperature have become core or high-tech representatives, such as European Large-scale scientific installations such as the Hadron Collider. According to international agreements, low-temperature refrigeration technology covers the temperature range below 120K. At present, the refrigeration method of the entire low-temperature temperature range is relatively mature. Superfluid helium, liquid helium or other lo...

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Problems solved by technology

Pulse tube refrigerators, GM refrigerators, and Stirling refrigerators are three typical regenerative refrigerators, in which pulse tube refrigerators have no moving parts at the cold end and have potentially high reliability, while according to the existing public literature According to the data, in the current regenerative refrigeration technology, only the low-frequency pulse tube refrigerator using helium-3 as the working fluid can obtain the refrigeration temperature of 1-2K, but it needs a large amount of helium-3, Jiang Ning et al. (Jiang N, et al . Cryogenics, 2004, 44: 809.) The lowest refrigeration temperature of 1.27K was obtained by using a two-stage low-frequency pulse tube refrigerator, but a total of 3228 liters of helium in the standard state were used

[0007] Helium-3 is one of the isotopes of helium gas, and its content in nature is very small. The volume fraction of normal helium gas is only 1.3×10 -6 % of helium-3 is a rare and expensive gas. At the same time, the United States, the main exporter of helium-3, has introduced relevant policies to limit the export of helium, which has led to a surge in the price of helium-3 in recent years. The current price of helium-3 is about 200 US dollars / standard liter, which rose to 2,000 US dollars / standard liter in 2009. The current price of helium-3 is about 10,000 US dollars / standard liter, which is expensive and the source is not easy to obtain

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